Desenvolvimento de Dispositivo para Estudo de Doppler Transcraniano: Comparação de Diferentes Exercícios Físicos e seus Efeitos na Circulação Cerebrovascular, na Função Executiva e na Memória de Adultos Saudáveis

Abstract

High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) consist of aerobic exercise modalities that provide performance gains in physical health through different metabolic pathways. The implications depending on the training modality on cerebrovascular function are still scarce. One way to assess cerebrovascular function is through transcranial Doppler ultrasound (TCD), despite the technical difficulty in performing this exam. These factors motivate studies to create tools to improve the TCD application process and define the implications of each training session on aspects of cerebral blood flow. Thus, the present thesis aims to design, manufacture and apply a new equipment capable of facilitating the use of the TCD exam. A second objective was to investigate changes in cerebrovascular circulation, lactate, and cognitive functions after different training sessions (HIIT and MICT). In this thesis, the design and development of a technological product was carried out, in addition to a randomized crossover study with two comparison situations. In the development of the technological product, it was designed in 3D software and manufactured by rapid prototyping in a 3D printer, a low-cost helmet for attaching a transducer and aiding in the TCD examination. A comparison of the TCD measurements was performed, with and without the use of the proposed helmet, in 26 individuals. The variable end-diastolic velocity (EDV) was used, as it is a value directly obtained by processing the echographic signal of the exam. The intraclass correlation coefficient (ICC) was considered good (R = 0.864). The use of the developed helmet facilitated the performance of the TCD exam, allowing for less time, greater convenience of handling for the operator and the potential of better standardization of the result obtained. The device proposed and used in the work had its patent deposited at the National Institute of Industrial Property (INPI), process registration BR 10 2020 025697 1. Regarding the randomized crossover study, the acute effect of HIIT and MICT exercises was compared in healthy adults, through cognitive function (working memory and executive function), serum lactate and cerebrovascular circulation variables: peak systolic velocity (PSV), EDV, pulsatility index (PI), resistivity index (RI) and heart rate (HR), with TCD for the right and left sides. The present study was approved by the research ethics committee, under number 5,023,567 (10/06/2021). The clinical trial involved 27 healthy young adults (14 men and 13 women, 23 ± 3 years). Immediately after a 14-minute physical exercise session (HIIT and MICT), a significant difference was observed, with an increase in HR and lactate in both conditions (p < 0.001). For the HIIT intervention, there was an improvement in executive function/semantic fluency, assessed by the verbal fluency test (p = 0.019). The other data evaluated in the TCD remained stable, except for the PI (p = 0.029) and RI (p = 0.023) for the MICT, with no significant difference (pre vs. post or HIIT vs. MICT) for the most part, reinforcing the regulator ability of cerebrovascular circulation, for the acute effect investigated. In addition, there was an improvement in cognitive performance associated with the increase in lactate for HIIT (ρ = 0.436; p < 0.001), corroborating findings in the literature, related to the benefit of this molecule as an energy substrate in the central nervous system.